How to Design an Outdoor Lighting System
For a step by step guide on designing a landscape lighting system,
follow these links or just scroll down the page.
Why use a low voltage system?
What is a low voltage system?
A low voltage system runs at 12 volts,
about 10 times smaller than the standard voltage for normal household use. (120
volts)
Why use a low voltage system for landscape lights?
Low voltage systems are becoming more and more popular
for landscape lighting. Not only is it safer and easier to install, but a low voltage
system provides the necessary power to highlight or accent your landscape
features. Low voltage cable can be buried in a shallow trench or even laid
on top of the ground. Conduit isn't necessary for the underground
wires. A low voltage system is also flexible so that you can change your
lighting, move fixtures or even add more fixtures to accommodate the changing
plant growth. By reducing the voltage, the risk of electrical shock
virtually disappears in case wires are accidentally cut. The lamps in
a low voltage system use less power, while still providing comparable
performance to similar, high-wattage 120 volt lamps.
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What should I light?
 What kinds of things in my landscape should I light?
The first step in designing any landscape lighting system is to determine
what you want the light to do for you. Take a walk around your property,
look out your windows and doors to figure out what kind of mood you want.
Look for possible focal points for a dramatic effect. Are you looking for
safety, to distinguish the steps on a stairway or to highlight the edge of
the driveway? Do you have any garden art you want to be able to see at night?
Which techniques should I use?
To help get your creative juices flowing, check out our page on
landscape lighting techniques.
Terms like uplighting and downlighting my not mean much to you now,
but the descriptions and pictures should stimulate new landscape lighting
ideas.
After reviewing the techniques, select those that will best achieve the mood
you're looking to create. Remember that some light will "spill"
from the accented area. Balance and subtlety are key tools in landscape
lighting. It is extremely easy to light an area too much. The key
phrase to remember should be "less is more."
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Which fixtures should I use?
Once you have an idea of what you
want to light, select the style of fixture and lamp based on your needs.
This is an important concept. It is too easy to pick the light that looks
the coolest and then decide what you want to light with it. It will
generally not produce the desired effect you want. Check out the
landscape lighting techniques
page again and this time notice which fixtures are associated with each
specific technique. Once again...sometimes less is more. You do not
necessarily need high levels of illumination coming from individual
fixtures. Instead, think about lighting an object from multiple angles
with softer light rather than one very bright fixture in front of it.
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Do I need a transformer?
For
a low voltage system, you do need a transformer. It is the power
console for your landscape lights that converts the voltage of household
outlets at 120 volts to 12 volts. Remember that the light
fixtures will not plug into a standard outlet.
How do I know which transformer to use?
To determine the transformer size you will need, add up the wattages
of all lamps you plan on using. Select a transformer that matches as
closely as possible the total lamp wattage.
For example: If you have 11 fixtures all rated at 24.4 watts,
you will need a 300 watt transformer.
(11 x 24.4 = 268.4 watts)
A few things to keep in mind:
-
The total lamp
load should not be less than one third the transformer's wattage
rating, nor exceed its maximum wattage capacity. If your
total wattage is too high, either divide the load between two transformers
or use a more powerful transformer.
-
We recommend you
get a transformer that will allow you to add fixtures at a later
time.
Since the transformer will be the most expensive part of your investment,
it's a good idea to plan ahead. Quite a few of our clients have come
back the following year or two and wanted to add to their landscape
lighting. Plus you only pay for the electric that you use. Just
because a transformer is rated for 300 watts doesn't mean it
is continually using 300 watts.
Here is some more information
on our Hadco©
transformers.
What is a multi-tap terminal on a transformer?
Once you have
selected an appropriate transformer, you will have a choice of
attaching the cable to the 11 volt, 12 volt or 13 volt terminal on
the terminal strip.
In essence, this allows you to pick the brightness of the lamps you will be
running on this circuit. The lower the voltage, the lower the
lamp will burn and thus last longer.
More than one length
of cable may be attached to each terminal provided the total wattage on all runs
does not exceed 300 watts.
So how do I select the correct power console (transformer) and terminal to use?
The primary
objective is to choose a console that has enough wattage to operate
the fixtures on the circuit. A common misconception is the higher the wattage
rating for the transformer, the longer the cable runs you can make. In
reality, it is the voltage, not wattage that is reduced by cable
resistance.
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What kind of cable do I need?
We recommend using
#12-2 low voltage cable for your landscape lights. As a general
rule of thumb, cable runs should not exceed 100 feet.
How should I run my cable lines?
There are a variety
of layouts for your landscape lighting design. This can be an important
factor in minimizing voltage drop.
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1.
Straight run installation
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Fixtures run in sequence directly from the transformer. Note:
This type of installation is not recommended for runs longer than one or two fixtures,
where you need a balanced light scheme.
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2.
Loop installation
- Helps reduce voltage
drop and produces a more uniform light output. It is important
that you connect the same wire leads to the proper transformer
terminals by noting the ridge or marking on one side of the cable.
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3.
Split load installation
- Run up the maximum cable length in two or more directions from the transformer.
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4.
T-installation
- Allows more equal
distribution of power to the center of a run, or to a run some
distance away. Cable running from the transformer must
be of a heavier gauge (8 or 10 gauge).
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How should I plan my layout?
 The
layout itself can be accomplished by sketching a view of the property,
including all landscape features to be illuminated. Mark the location of each
fixture and power console. Draw a dotted line from the power console to
each fixture to denote the cable, remembering to center feed to the load of the
run. Try to avoid running the cable under walks and drives more than once
to eliminate the need for extra work when installing. Keep a copy of the
plan as a reference for expansion or excavation work. Click on
the picture for a sample layout.
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What is voltage drop?
The voltage drop in an electrical
system is the change in voltage from one point to another in the line. The
closer the lamps are to the transformer, the higher their voltage and wattage
readings will be. Those fixtures farthest away will have a lower voltage
and wattage. So why is this important? The higher the voltage and
wattage, the brighter the bulb will burn. If a cable run is too long, or
if too many lights are being powered by a single transformer, noticeable voltage
drop may occur. Lights furthest from the transformer will be dimmer than
those closer to it. (Of course this can actually work to your
advantage if the differences in lamp brightness levels are not objectionable.)
How can I prevent voltage drop?
Voltage drop can be minimized in several different ways:
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Use heavier gauge cable (8 or 10 gauge).
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Use a higher rated transformer.
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Use multiple transformers.
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Shorten the cable lengths.
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Reduce individual fixture wattages.
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Reduce the number of fixtures on a run
Is voltage drop necessarily a Bad thing?
Voltage drop can actually work to
your advantage if differences in lamp brightness levels are not
objectionable. For example, is there an area of your yard you want to be
less bright than the rest? If so, it would be OK to put a light at the end
of one of your cable runs, where the voltage is less. Running
landscape lights at a lower voltage can also extend the life of the
lamps, requiring less frequent replacement.
Our page on
Voltage Drop
offers more details on calculating the voltage drop and other tips.
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Are there any other accessories I will need?
By now you should have a list of
fixtures, their lamps, cable and one or more transformers. The
only thing left you may need are mounting accessories like stems, stakes
or shielding devices.
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For more information on Landscape Lighting, please call Nida Lighting
at
800.761.6432
or email us at
info@nidagroup.com.
Landscape Lighting Home
Fixtures |
Transformers |
Design |
Techniques
Installation |
Maintenance |
Troubleshooting
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The
layout itself can be accomplished by sketching a view of the property,
including all landscape features to be illuminated. Mark the location of each
fixture and power console. Draw a dotted line from the power console to
each fixture to denote the cable, remembering to center feed to the load of the
run. Try to avoid running the cable under walks and drives more than once
to eliminate the need for extra work when installing. Keep a copy of the
plan as a reference for expansion or excavation work. Click on
the picture for a sample layout.